Wednesday, January 20, 2016

Seminar-Perspectives of terahertz and multi-terahertz spectroscopy in the time domain

Speakers: Petr Kužel (Fyzikální ústav AV ČR, oddělení dielektrik) 
Place: lecture hall of IoP, Slovanka
Organisers: Department of Dielectrics

Seminar Tuesday, 01/26/2016 10:00 - 11:00

Is there any deep reason of using the new (and trendy) words “terahertz” and “multi-terahertz” when the traditional and well-established terms of far-infrared and mid-infrared have been available for decades? The answer is that the terms (multi-)terahertz are closely connected to specific quasi-optical techniques of coherent generation and detection of radiation, which provide some added value compared to “classical” experimental methods.
The standard terahertz range 0.1–3 THz represents a border between the electronics and optics worlds where virtually no efficient radiation sources were available until recently. In the historical context the (pulsed) time-domain terahertz spectroscopy was invented as a technique closely related to the development of femtosecond (optical) lasers. The method of the detection of THz pulses — so called “electro-optic gating” — brings several benefits: high sensitivity at low powers, direct measurement of electric field of the radiation (i.e. phase sensitivity) and sub-picosecond time resolution. It allows one to observe directly the oscillations of terahertz light during various interactions.
Later on, it has been realized that the same principles can be used for the generation and detection of ultrashort mid-infrared (i.e. multi-THz) pulses continuously up to ~ 60 THz and that also high-field (up to 10 MV/cm or 3 T) terahertz nonlinear table-top experiments can be easily carried out.
Finally, related recent and future developments of the THz lab at FZU will be discussed.

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